Percussion type hand tool for separating two members



May 31, 1966 H. LEHN 3,253,329

PERCUSSION TYPE HAND TOOL FOR SEPARATING TWO MEMBERS Filed March 20, 1964 INVENTOR HENRY LEHN BY: M

PATENT AGENTS 3,253,329 PERCUSSION TYPE HAND TOOL FGR SEPARATING TWU MEMBERS Henry Lehn, 50 Glenview Ave., Gait, Ontario, Canada Filed Mar. 20, N64, Ser. No. 353,417 2 Claims. (Cl. 29-275) The present invention is concerned with improvements in or relating to hand tools for separating two members and especially, but not exclusively, such tools for separating the casing and the core of a hydraulic valve lifter.

Since the introduction of hydraulic valve lifters they have become generally adopted, because of their convenience in avoiding the need for regular tappet adjustments. Such lifters usually comprise a hollow cylindrical outer body, called herein the casing, sliding in a bore in the engine block and forming a cylinder, and a cylindrical inner body, called herein the core, sliding in a bore in the outer body and forming a piston. The interior of the cylinder is supplied at appropriate times with oil under pressure via a non-return valve, so that the lifters automatically adjusts in length to the distance between the respective cam and valve tappett.

After a period of use sticky deposits from the oil begin to interfere with the proper operation of the lifters, and this interference frequently becomes so severe that one or more of the lifters becomes completely inoperative, and must be removed from the engine and cleaned. A particularly suitable manipulative hand tool for such removal is disclosed and claimed in my copending application Serial No. 353,494, filed concurrently with the present application. It is commonly found upon removal of the lifter that because of the said deposits the core is no longer freely slidable in the casing and cannot be removed by hand. This separation must be effected without damage to the highly-finished mutually sliding surfaces of the core and casing, or the relatively expensive lifter may be so damaged as to render it useless for fur ther operation.

It is an object of the present invention to provide a new hand tool for separating two members.

It is another object of the present invention to provide a new hand tool adapted for the separation of two members which slide one within the other in a manner ensuring that highly-finished, mutually-sliding surfaces thereof are not damaged.

It is a further object of the present invention to provide a new hand tool adapted for the ready separation of the core and casing of a hydraulic valve lifter without damage thereto.

According to the present invention there is provided a new hand tool for separating two members slidable one within the other comprising a head member having a striking surface, a handle member for engagement by an operator in moving the head member, a first bore in the head member adapted to receive therein the outer one of the said two members, a second bore in the head member opening into the first bore and disposed nearer to the striking surface than the first bore, and means between the two bores adapted to permit entry of the inner one of the said two members into the second bore and to prevent entry therein of the said outer member upon the said striking surface being struck against another surface.

A hand tool which is a particular preferred embodiment of the invention, especially suitable forthe separation of the casing and the core of a hydraulic valve lifter, will now be described, by way of example, with refer ence to the accompanying diagrammatic drawing showing the tool generally in side elevation but with part of its side wall broken away so that the interior can be seen.

The tool consists generally of a head member 1 and a nitecl States Patent handle 2. In this embodiment the handle is separable from the body member and is connected thereto by a screw-threaded portion 3 which engages in a correspond ing screw threaded bore 4 in the head member, so that the same handle can be used with head members adapted for use with different sizes of valve lifters.

The head member comprises an elongated hollow cylinder of circular cross section and closed at one end, the closed end being provided with a curved striking surface 5 for a purpose described below.

The interior of the head is provided with a bore 6 of circular cross-section, and of diameter suflicient to permit the casing 7 of a valve lifter to slide freely therein without substantial sideways play. For example, with a casing of one inch diameter the bore 6 may provide a diametrical clearance of l5-20 thousandths of an inch. The bore 6 leads into another bore 8, also of circular cross section, disposed nearer to the striking surface 5, and of diameter sufiicient to permit the lifter core 9 to slide freely therein, but not sufficient to permit entry of the casing 7, so that an annular casing retaining shoulder 10 is formed between the two bores. A cylindrical oil reservoir 11, of smaller diameter than the bore 8, is provided at the end of the latter nearer to the striking surface to receive any oil that escapes from the lifter upon separation of its core and casing, an annular core retaining shoulder 12 being formed between the bore 8 and the reservoir 11. A combined air escape and viewing aperture 3 extends through the side wall of the head member from the bore 8 to the outside of the member.

The length of the bore 6 is substantially greater than the lifter casing and the casing is able to slide freely longitudinally therein to an extent determined at one end by the annular surface 10, and at the other end by a removable, diametrically-disposed stop pin 14. In a practical embodiment intended for use with a lifter casing of length 2 /8 inches the distance between the stop pin and the surface 10 is 3 /8 inches. The length of the bore 8 is such that with the core therein it is just completely sep arated from the casing. In a practical embodiment the stop pin 14 can be a split pin with its centre portion widened, so that the said centre portion must be compressed to insert the pin in its bores.

In operation the lifter is slid into the bore 6 and the pin 14 placed in position. By use of the handle 2 the head is struck heavily on any suitable solid member serving as an anvil, the direction of striking being longitudinally of the bores 6 and 8 so that the face 5 engages he anvil. It will be apparent that the tool constitutes a hammer and the surface 5 can be rounded to any contour found suitable for a hammer striking surface. If the core and casing are stuck firmly together several heavy blows will be needed to separate them, and as the tool is swung upward for a blow the casing slides along the bore 6 until it engages the stop pin 14. As the tool descends inertia will also press the casing against the stop pin. At the moment of impact the casing will slide downwards in the bore 6 until it is stopped suddenly by the shoulder 10, so that its own kinetic energy is added to that of the head in acting to separate it from the core. The practical importance of permitting free sliding movement of the core is illustrated by the fact that I have always been able to separate even the most stubbornly stuck lifter parts with about five or six heavy blows, whereas it is sometimes impossible to separate them at all if the pin 14 is moved to a position in which no longitudinal sliding movement of the casing is permitted.

As the core is freed from the casing any air trapped ahead of it can escape through the bore 13. Moreover, at any time the operator can look through the bore to check whether the core has been freed. The lifter always contains a small amount of oil and this will be discharged into the reservoir 11; it may be noted that the bore 13 must not open into the bore 8 too close to the reservoir 11 or it is found that this oil is projected violently through the bore 13 and sprayed over the surroundings.

Different Ways of manufacturing the tool will be apparent to those skilled in the art. For example, both the bores 6 and 8 can be drilled using separate drills of the required diameter, or the bore 8 may be formed by an annular sleeve fitting within a suitable extension of the bore 6. Other modifications of the invention within the scope of the appended claims will be apparent to those skilled in the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A hand tool for separating two coaxial members which comprises an inner member slidable in a bore in an outer member, the tool comprising a hollow head member having a longitudinal axis and a front striking surface transverse to the said axis, a handle member extending from the head member for grasping by an operator in moving the head member in directions generally parallel to the said longitudinal axis to strike the front striking surface against another surface, first and second coaxial bores in the head member coaxial with one another and with the said longitudinal axis, the said first bore opening to the rearof the head member in the direction away from the striking surface for reception of the coaxial members therein, being of appreciably greater length than the said outer member, and permitting free sliding movement therein of the outer member, the said second bore being disposed nearer to the front striking surface than the first bore, and being of smaller dimension than the first bore transverse to the longitudinal axis to receive the inner member therein for free sliding movement and to prevent entry therein of the outer member, an annular shoulder at the junction of the two bores for impact engagement by the outer member upon striking of the head member against said another surface, and removable stop means for closing at will the said open end of the first bore through which the coaxial members are inserted into the head member a distance from the said annular shoulder such as to permit free sliding movement of the outer member rearward into engagement with the stop means and out of engagement with the shoulder upon corresponding rearward movement of the head member, and forwards into impact engagement with the shoulder upon the corresponding forward movement and striking of the head member.

2. A hand tool as claimed in claim 1, and comprising References Cited by the Examiner UNITED STATES PATENTS 10/1948 Heinrich. 10/1957 Sandell 29255 .WILLIAM FELDMAN, Primary Examiner.

MYRON C. KRUSE, Examiner. 

1. A HAND TOOL FOR SEPARATING TWO COAXIAL MEMBERS WHICH COMPRISES AN INNER MEMBER SLIDABLE IN A BORE IN AN OUTER MEMBER, THE TOOL COMPRISING A HOLLOW HEAD MEMBER HAVING A LONGITUDINAL AXIS AND A FRONT STRIKING SURFACE TRNSVERSE TO THE SAID AXIS, A HANDLE MEMBER EXTENDING FROM THE HEAD MEMBER FOR GRASPING BY AN OPERATOR IN MOVING THE HEAD MEMBER IN DIRECTIONS GENERALLY PARALLEL TO THE SAID LONGITUDINAL AXIS TO STRIKE THE FRONT STRIKING SURFACE AGAINST ANOTHER SURFACE; FIRST AND SECOND COAXIAL BORES IN THE HEAD MEMBER COAXIAL WITH ONE ANOTHER AND WITH THE SAID LONGITUDINAL AXIS, THE SAID FIRST BORE OPENING TO THE REAR OF THE HEAD MEMBER IN THE DIRECTION AWAY FROM THE STRIKING SURFACE FOR RECEPTION OF THE COAXIAL MEMBERS THEREIN, BEING OF APPRECIABLY GREATER LENGTH THAN THE SAID OUTER MEMBER, AND PERMITTING FREE SLIDING MOVEMENT THEREIN OF THE OUTER MEMBER, THE SAID SECOND BORE BEING DISPOSED NEARER TO THE FRONT STRIKING SURFACE THAN THE FIRST BORE, AND BEING OF SMALLER DIMENSION THAN THE FIRST BORE TRANSVERSE TO THE LONGITUDINAL AXIS TO RECEIVE THE INNER MEMNER THEREIN FOR FREE SLIDING MOVEMENT AND 